The two DIVs in question are the #primary and #secondary. In Safari they line up and position themselves side by side. But on the iPhone, the #secondary DIV is spilling over and is positioned underneath the #primary. Is that something someone could help me with? Is it simply my math is off a bit?

Make sure that you have declared position:relative and float:left to both divs, that they do not have widths declared, that the container div is wide enough to hold both divs at the same level and that both of them divs are not clearing anything (clear:none). Also if you have issues getting the container div to span the whole height of the contained floated divs set its overflow to auto. This should fix your problem.